Magneto-optic switch

ABSTRACT

Systems, methods, and apparatus for optical switching. In some implementations, a magneto-optic switch includes multiple optical components positioned in order along a light path including: a single optical fiber collimator, a first pair of refraction crystals, a first half wave plate assembly, refraction components, a second half wave plate assembly, a second pair of refraction crystals, and a dual fiber optic collimator, wherein a first side of the refraction components near the first half wave plate assembly includes a first Faraday effect element, a second side of the refraction components near the second half wave plate assembly includes an optic rotation assembly, the optic rotation assembly having a magnetic field generating component outside the first Faraday effect element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Chinese patent application 201210480020.4, filed Nov. 22, 2012, the disclosure of which is incorporated herein by reference.

BACKGROUND

This specification relates to optical fiber communication systems and more specifically to magneto-optic switches.

Conventional optical fiber communication systems use a large number of various types of magneto-optic switches, to achieve light beam switching between one input optical fiber and multiple optical fibers or between multiple optical fibers and one optical fiber. Magneto-optic switches are typically used in the optical fiber communication industries, instrument industries, and defense industries.

Typical optic switches are primarily divided into mechanical optic switches and non-mechanical optic switches. Optical switch technologies can include micro electromechanical systems (MEMS) technology, liquid crystal technology, thermo-optic effect, electro-optic effect, magneto-optic technologies, etc. Mechanical types of optic switch technologies have advantages including a low production cost, a broad bandwidth and a low loss, etc. However, at the same time, they also suffer from drawbacks including a large size, short life, poor repeatability, long switching, etc. Advantages of optic switches applying the MEMS technology, thermo-optic effect, and liquid crystal technology include a small size and quick switching. However, due to the fact that these optic switches involve fine semiconductor processing technologies with complex processes, their production cost has risen substantially. Advantages of non-mechanical magneto-optic switches include a lack of mechanical part movements, a high repeatability, and a short switching, etc.

FIG. 1 is a structural diagram of a conventional magneto-optic switch 100. An optical fiber 12 is installed in optical fiber collimator 11. Along a direction of a light path, the magneto-optic switch 100 includes a dual refraction crystal 13, half wave plate assembly 14, Faraday effect element 16, dual refraction crystal optic conductors 17, dual refraction crystal light beam deflectors 18, Faraday effect element 19, half wave plate assembly 21, dual refraction crystals 22, and dual optical fiber collimators 23 are positioned in sequence. Two parallel optical fibers 24 are installed in dual optical fiber collimators 23. Outside of Faraday effect elements 16 and 19, magnetic field generating component 15 and 20 are separately positioned.

After a light beam is emitted from the optical fiber 12 of the single optical fiber collimator 11, it forms two light beams with identical directions of propagation after passing through the dual refraction crystals 13. The polarization states of the two light beams are perpendicular to each other. After the two light beams pass through the half wave plate assembly 14, the directions of propagation remain unchanged, but the polarization states are identical. Furthermore, the two light beams pass through the Faraday effect element 16, causing polarization states experience a diversion.

In particular, when linear polarized light with a fixed polarization state passes through the Faraday effect element 16 under a different magnetic field, their polarization states and directions of polarization are not exactly identical. The dual refraction crystal optic light conductors 17 and dual refraction crystal optic light beam deflectors 18 have different conversion rates for light beams with different polarization states. Thus, after light beams with different polarization states pass through dual refraction crystal light conductors 17 and dual refraction crystal light beam deflectors 18, their directions of propagation will experience different changes. Using this characteristic, and by changing the direction of the current of the coil in magnetic field generating component 15, the magneto-optic switch changes the magnetic field polarity generated by the magnetic field generating component 15. This further changes the polarization states of light beams passing through the Faraday effect element 16, and changes the directions of propagation of light beams after they pass through the dual refraction crystal light conductors 17 and the dual refraction crystal light beam deflectors 18.

After light beams pass through the dual refraction crystal light conductors 17 and the dual refraction crystal light beam deflectors 18, sequentially, they pass through the Faraday effect element 19 and half wave plate assembly 21, before being emitted to the dual refraction crystals 22. The two light beams that pass through the half wave plate assembly 21 merge into one beam inside the dual refraction crystals 22, and then are emitted out of the optical fiber 24 inside the dual optical fiber collimators 23.

Because a change of the magnetic field polarity generated by the magnetic field generating component 15 can change the directions of propagation of light beams passing through the dual refraction crystal light conductors 17 and the dual refraction crystal light beam deflectors 18, it is possible to select which optical fiber 24 inside the dual optical fiber collimators 23 the light beams will be directed toward, thus providing selection of a light path resulting in optical switching.

Additionally, the optical fibers installed in the single optical fiber collimator 11 and the optical fibers 12 and 24 installed in the dual optical fiber collimators 23 are ordinary optical fibers, thus the light spot of light beams being emitted from the optical fiber 12 has a large radius and a significant dispersion, requiring the use of relatively bulky dual refraction crystals 13 and 22. Thus, the Faraday effect elements 16 and 19, dual refraction crystal light conductors 17, and dual refraction crystal light beam deflectors 18 can all be relatively bulky. Additionally, it may be necessary to place certain clearances between the dual refraction crystal light conductors 17 and the dual refraction light beam deflectors 18, making it difficult to reduce the sizes of the Faraday effect elements 16 and 19, dual refraction crystal light conductors 17, and dual refraction crystal light beam deflectors 18.

In addition, the magnetic field generating components 15 and 20 normally include a coil wound iron core, on which coils are wound. Because the Faraday effect elements 16 and 19, dual refraction crystal light conductors 17, and dual refraction crystal light beam deflectors 18 are relatively bulky, it can be difficult to place the components in the same iron core. The use of two magnetic field generating components 15 and 20 is typically required to respectively load magnetic fields into the Faraday effect elements 16 and 19, leading to a higher number of components used by magneto-optic switches and bulkier components. This can raise the production cost of magneto-optic switches and increase the packaging difficulty.

SUMMARY

In general, one innovative aspect of the subject matter described in this specification can be embodied in a magneto-optic switch that includes multiple optical components positioned in order along a light path including: a single optical fiber collimator, a first pair of refraction crystals, a first half wave plate assembly, refraction components, a second half wave plate assembly, a second pair of refraction crystals, and a dual fiber optic collimator, wherein a first side of the refraction components near the first half wave plate assembly includes a first Faraday effect element, a second side of the refraction components near the second half wave plate assembly includes an optic rotation assembly, the optic rotation assembly having a magnetic field generating component outside the first Faraday effect element.

The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. The single optical fiber collimator is single core light beam expansion collimator and wherein a light beam expansion optical fiber is installed in the single core light beam expansion collimator. The dual optical fiber collimator is a dual core light beam expansion optical fiber collimators and wherein two light beam expansion optical fibers are installed in the dual core light beam expansion optical fiber collimator. The first Faraday effect element of the optic rotation assembly, the refraction components, the optic rotation component, and the magnetic field generating component are integrally packaged. The optic rotation component is a second Faraday effect element. The second Faraday effect element is located inside the magnetic generating component. The optic rotation component is a half wave plate. The refraction component is a Wollaston prism or a pair of mutually adjacent wedge dual refraction crystals. The first half wave plate assembly has a first a half wave plate, the first half wave plate being located on a light path of a light beam emitted from the first dual refraction crystals. The second half wave plate assembly has a second half wave plate, the second half wave plate being located on a light path of a light beam emitted from the second dual refraction crystals. The second half wave plate assembly includes a compensation plate, the compensation plate being located on the light path of another light beam where the second half wave plate is located. The first half wave plate assembly and the second half wave plate assembly, respectively, include two half wave plates, the two half wave plates in the same set of half wave plate assemblies are respectively located on the light paths of two light beams emitted from the first dual refraction crystals.

Particular embodiments of the subject matter described in this specification can be implemented so as to realize one or more of the following advantages. A less bulky magneto-optic switch can be provided as compared to some conventional magneto-optic switches. Additionally, a magneto-optic switch is provided that uses fewer components. Because the size of the components in the optic rotation assemblies are smaller, it is possible to integrally package the components, forming an integrated module and simplifying the packaging process of magneto-optic switches, thus also improving the efficiency of magneto-optic switches.

The details of one or more embodiments of the subject matter of this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a conventional magneto-optic switch.

FIG. 2 is an optic structural diagram of an example magneto-optic switch.

FIG. 3 is a structural diagram of an example light beam expansion optical fiber.

FIG. 4 is an optic structural top view of the magneto-optic switch of FIG. 2.

FIG. 5 is an optic structural main view of the magneto-optic switch of FIG. 2.

FIG. 6 is a diagram of an example light beam polarization state of the magneto-optic switch of FIG. 2 under a first work state.

FIG. 7 is a diagram of the light beam polarization state of the magneto-optic switch of FIG. 2 under a second work state.

FIG. 8 is an optic structural diagram of another example magneto-optic switch.

Like reference numbers and designations in the various drawings indicate like elements.

DETAILED DESCRIPTION

The magneto-optic components disclosed in the present specification can achieve a switching between one input optical fiber and multiple output optical fibers as well as the switching between multiple input optical fibers and one output optical fiber.

FIG. 2 is an optic structural diagram of an example magneto-optic switch 200. The magneto-optic switch 200 includes a single optical fiber collimator 31. An optical fiber 32 is installed in the single optical fiber collimator 31. In some implementations, the single optical fiber collimator 31 includes a single core light beam expansion collimator and the optical fiber 32 is a light beam expansion optical fiber. On the emitting end of the single optical fiber collimator 31, along the direction of the light path, the magneto-optic switch 200 includes optical components including dual refraction crystals 33, half wave plate assembly 34, optic rotation assembly 36, half wave plate assembly 43, dual refraction crystals 46, and dual fiber optic collimators 47 are positioned in order. Two parallel optical fibers 48 are installed in dual optical fiber collimator 47. In some implementations, the dual fiber optic collimator 47 is a dual core light beam expansion collimator. In some implementations, the two optical fibers 48 are both light beam expansion optical fibers.

FIG. 3 is a structural diagram of an example light beam expansion optical fiber. An optical fiber 32 includes a fiber core 51 and a wrapping layer 50 that is wrapped outside of fiber core 51. At a first end of the optical fiber 32, the radius of fiber core 51 expands rapidly, forming an expanded area 52. As a result, a radius of a light spot of a light beam emitted from the single core light beam expansion fiber collimator 31 is reduced. The two optical fibers 48 installed in dual optical fiber collimators 47 are also light beam expansion fibers, whose structures are similar to the structure of optical fiber 32.

Returning to FIG. 2, the half wave plate assembly 34 includes a half wave plate 35. The half wave plate 35 is located on one of the light paths of the two light beams emitted from the dual refraction crystals 33. The half wave plate 35 is located on a side of a lower end, as shown in FIG. 2, near the dual refraction crystals 33. The half wave plate assembly 43 includes a half wave plate 44 and a compensation plate 45. The half wave plate 44 is located on the light path of the same light beam for the half wave plate 35. By contrast, the compensation plate 45 is located on the light path of the other light beam opposite the light beam for the half wave plate 44. The half wave plate 44 is located on a side near the lower end, as shown in FIG. 2, of the dual refraction crystals 46, whereas the compensation plate 45 is located on a side near an upper end, as shown in FIG. 2, of the dual refraction crystals 46.

The half wave plates 35 and 44 have a phase delaying function for light beams passing through them. After a light beam passes through the half wave plates 35 and 44, the phase will experience a delay, thus changing the polarization state of the light beam. After the light beam passes through the half wave plates 35 and 44, the phase delay is half of a phase. Consequently, the polarization state will experience a 90° rotation.

By setting optic axis angles of the half wave plates 35 and 44 and the angle of the polarization direction of linear polarized light emitted onto half wave plates 35 and 44, a 90° rotation of the polarization state of the half wave plates 35 and 44 for linear polarized light occurs. In some other implementations, the directions of the optic axes of half wave plates can be changed such that the rotation angle of the polarization direction of linear polarized light after passing through a half wave plate may not be 90°.

The compensation plate 45 has a phase delaying function for a light beam that passes through the compensation plate 45 corresponding to a phase delay of one phase. Therefore, the polarization state of the linear polarized light will not be changed. Of the two light beams emitted from the dual refraction crystals 33, one light beam will pass through the half wave plates 35 and 44 such that its phase experiences a one phase delay. To ensure the phase synchronization of two light beams, another light beam passes through the compensation plate, to achieve a one phase delay, thus ensuring synchronization of the phases of the two light beams emitted onto the dual refraction crystals 46.

The optic rotation assembly 36 includes a refraction component. In some implementations, the refraction component is a Wollaston prism 37 that includes a pair of wedge prisms 38 and 39. The optic axes of the wedge prisms 38 and 39 are perpendicular to each other. On the two ends of Wollaston prism 37, Faraday effect elements 40 and 41 are respectively positioned. The Faraday effect element 40 is positioned on a side near the half wave plate assembly 34, and the Faraday effect element 41 is positioned on a side near the half wave plate assembly 43.

A magnetic field generating component 42 is positioned outside the Faraday effect elements 40 and 41. The magnetic field generating component 42 includes a circular iron core. A coil is wound onto the circular iron core. Electrical currents selectively applied in different directions are passed through the coil to generate magnetic fields with different polarities on the iron core. In addition, the Wollaston prism 37 and Faraday effect elements 40 and 41 are positioned inside the magnetic field generating component 42. In some implementations, the Wollaston prism 37, Faraday effect elements 40 and 41, and magnetic fields generating component 42 are integrally packaged, forming an integrated module 400, as shown in FIG. 4. The Faraday effect elements 40 and 41 are respectively positioned adjacent to two side walls of the Wollaston prism 37. The magnetic field generating component 42 is positioned outside of the Wollaston prism 37 and the Faraday effect elements 40 and 41.

The single optical fiber collimator 31 is positioned on the optical input end of the magneto-optic switch 200, forming an optical input port. The dual optical fiber collimator 47 is located on the optical output end of the magneto-optic switch 200. The dual optical fiber collimator 47 holds two light beam expansion optical fibers 48 used for outputting light beams, and thereby forming a first and a second optical output ports. As illustrated in FIG. 4, the optical output ports have a specified separation distance on axis Z, that is, the first and second optical output ports do not overlap.

FIG. 5 is an optic structural main view of the magneto-optic switch of FIG. 2. FIG. 6 is a diagram of an example light beam polarization state of the magneto-optic switch of FIG. 2 under a first work state, e.g., when a current is applied to the magnetic field generating component 42 is a first direction. After light beam L11 with a polarization state in a random popularization direction is emitted from the single optical fiber collimator 31, it enters the dual refraction crystals 33 and is separated into two light beams, L12 and L13, whose polarization states are perpendicular to each other. The optic axis of the dual refraction crystals 33 are within the X-Y plane and form a 45° included angle from both axis X and axis Y. Light beam L12 formed by the breakdown is an extraordinary light, whose polarization direction runs parallel to axis Y, and is emitted from the side near the upper end of the dual refraction crystals 33. Light beam L13 is an ordinary light, whose polarization direction runs parallel to axis X, and which is emitted from the side near the lower end of the dual refraction crystals 33.

After the light beam L12 is emitted from the dual refraction crystals 33, it forms light beam L14, and passes into the Faraday effect element 40. After light beam L13 is emitted from the dual refraction crystals 33, it forms light beam L15. The polarization state of light beam L15 is identical to the polarization state of light beam L13. It then passes into the half wave plate 35 and forms light beam L16. The polarization state of light beam L16 will experience a 90° rotation. Therefore, the polarization state of light beam L16 is identical to the polarization state of light beam L14, as both run parallel to axis Y.

On the X-Y plane, light beams L14 and L16 are two light beams distributed in the upper part and lower part, respectively. However, on the X-Z plane, light beam L14 overlaps with light beam L16 and are both located in positions on light beam L01, as shown in FIG. 4.

After light beam L14 and light beam L16 pass through the Faraday effect element 40, they respectively form light beams L18 and L19. A current is applied to the coil of the magnetic field generating component 42 in a first direction. The polarization states of two light beams L18 and L19 experience a 45° rotation relative to the polarization states of light beams L14 and L16 and the direction of polarization is a 45° clockwise rotation in the Y-Z plane.

After light beams L18 and L19 are emitted into the Wollaston prism 37, their polarization states do not change, but there is a change from extraordinary light to ordinary light. At the same time, the direction of propagation of light will experience a deflection to the forward direction of axis Z in the X-Z plane, but the angle of the deflection is normally small. As shown in FIG. 4, light beams L20 and L21 will propagate along the direction of light path L02.

After light beams L18 and L19 pass through the Wollaston prism 37, they respectively form light beams L20 and L21 and after light beams L20 and L21 pass through the Faraday effect element 41, the polarization state will again experience a diversion by continuing to rotate clockwise by 45° in the Y-Z plane. Consequently, the polarization direction of light beams L20 and L21 run parallel to axis Z.

Then, light beam L20 passes through the compensation plate 45 and forms light beam L22 and the polarization state will not change. However, a delay of one phase occurs when light beam L21 passes through the half wave plate 44 and forms the light beam L23. The polarization direction of the light beam L23 experiences a 90° rotation relative to the polarization direction of light beam L21. As a result, the polarization direction of light beam L22 and the polarization direction of light beam L23 are perpendicular to each other.

After light beam L22 and light beam L23 are emitted into the dual refraction crystals 46, they respectively form light beams L24 and L25 without change in polarization state. Light beams L24 and L25 are merged in the refraction crystals 46 to form light beam L26, which is emitted into optical fiber 48 of the dual optical fiber collimators 47. In particular, the light beam L26 is emitted into a first optical output port. Additionally, light beams L24 and L25 will propagate in the direction of light path L04 shown in FIG. 4.

Thus, by passing a current through the magnetic field generating component 42 in the first direction, the light path of light from the optical input port passes to a first optical output port.

If a current is applied to the magnetic field generating component 42 in a second direction (i.e., a reverse direction), the polarity of the magnetic field generated by the magnetic field generating component 42 changes. Consequently, after light beams L14 and L16 are emitted into the Faraday effect element 40, their polarization state rotates counterclockwise within the Y-Z plane by 45°. The resulting polarization direction of light beams L18 and L19 is shown in FIG. 7. However, on the X-Z plane, light beams L14 and L16 are still propagated along the direction of light path L01.

When a reverse current is applied to the magnetic field generation component 42, the polarization direction of light beams L18 and L19 is different from the polarization direction when the forward current is applied to the magnetic field generating component 42. Additionally, because the Wollaston prism 37 has a different refraction rate for linear polarized light in different polarization states, their directions of propagation are also different. Therefore, light beams L18 and L19 will propagate along the direction of light beam L03 in the Wollaston prism 37 in FIG. 4. That is, light beams L18 and L19 will experience a change from ordinary light to extraordinary light and the directions of propagation will be deflected to the negative Z axis direction in the X-Z plane.

After light beams L18 and L19 are emitted from the Wollaston prism 37, they form light beams L20 and L21 and are emitted into the Faraday effect element 41. The polarization directions of light beams L20 and L21 will experience another diversion compared to light beams L18 and L19. The polarization directions of light beams L20 and L21 both run parallel to axis Z.

After light beam L20 passes through the half wave plate 44, whose optic axis is 45° in the Y-Z plane, the polarization direction will rotate by 90°. After light beam L21 passes through the compensation plate 45, the polarization direction remains unchanged, but undergoes a phase delay of one phase. Light beams L22 and L23, whose polarization states are perpendicular to each other, are merged after being emitted into the dual refraction crystals 46 and propagated upward along the direction of light path L05 in FIG. 4. Light beam L26 formed after the merge is emitted into another light beam expansion optical fiber 48 of dual optical fiber collimators 47, thus achieving light path 03 from optical input port to the second optical output port.

Thus, by changing the directions of currents applied to the magnetic field generating component 42, the output ports of light beams can be changed to provide optic switching between output ports.

Since, the optical fiber 32 of the optical input end and the optical fiber 48 of the optical output end are both light beam expansion fibers, the radius of the light spot of the light beam emitted from the single core light beam expansion optical fiber collimator 31 is smaller. Therefore, the sizes of the dual refraction crystals 33 and 46 and the components in optical rotation assembly 36 can be compact in size. Consequently, two Faraday effect elements 40 and 41 can be placed in the same magnetic field generating component 42, which not only reduces the size of the magneto-optic switch, but also reduces the number of components used by the magneto-optic switch.

In some implementations, the Faraday effect element 41 can be replaced with a half wave plate. The half wave plate is used to rotate the polarization state of an incoming light beam by 45°. However, the crosstalk resistance performance of the magneto-optic switch will be substantially reduced. This is because the magneto-optic switch cannot achieve the isolation of light beams returning from optical output ports. Therefore, they may only be used in situations where the requirement for crosstalk resistance performance is not rigorous.

FIG. 8 is an optic structural diagram of another example magneto-optic switch 800. The magneto-optic switch 800 includes a single optical fiber collimator 61. An optical fiber 62 is installed in the single optical fiber collimator 61. On the emitting end of the single optical fiber collimator 61, along the direction of a light path, optical components can include dual refraction crystals 63, half wave plate assembly 64, optic rotation assembly 67, half wave plate assembly 73, dual refraction crystals 76, and dual optical fiber collimators 77 are positioned in order. Two parallel optical fibers 78 are installed in the dual optical fiber collimators 77.

The single optical fiber collimator 61 is a single core light beam expansion optical fiber collimator. The dual optical fiber collimator 77 is a dual core light beam expansion optical fiber collimator and optical fibers 62 and 78 are both light beam expansion optical fibers. Thus, the radius of the fiber optic cores near the end of the optical fibers increases rapidly, so that the radius of the light spot of the light beam emitted from the optical fiber 62 is larger.

The half wave plate assembly 64 includes two half wave plates 65 and 66, which are respectively located on the light paths of two light beams emitted from the dual refraction crystals 63. The function of the half wave plate assembly 64 is to change the polarization states of the two light beams from a mutually perpendicular state to a mutually parallel state. Therefore, the optic axes of the half wave plates 65 and 66 are not parallel.

The half wave plate assembly 73 also includes two half wave plates 74 and 75, which are also respectively located on the light paths of two different light beams. The function of the half wave plate 73 is to change the polarization states of the two incoming light beams from being parallel to each other to a state where the polarization states are perpendicular to each other. Therefore, the optic axes of the half wave plates 74 and 75 are not parallel.

The optic rotation element 67 includes a refraction component. The refraction component includes two mutually adjacent wedge dual refraction crystals 68 and 69 and the optic axes of the dual refraction crystals 68 and the dual refraction crystals 69 are perpendicular to each other. A Faraday effect element 70 is positioned on a side of the refraction component proximate to the half wave plate assembly 64 and a Faraday effect element 71 is positioned on a side proximate to the half wave plate assembly 73. In addition, the refraction component and the Faraday effect elements 70 and 71 all placed within the magnetic field generating component 67. In some implementations, the refraction component and the Faraday effect elements 70 and 71 and the magnetic field generating component 67 are integrally packaged.

By changing the directions of the currents applied to the magnetic generating component 67, the state of one of the two optical fibers 78 emitted from dual optical fiber collimator 77 can be changed to the state of the other optical fiber, thus changing the light path of optic propagation.

In some implementations, without consideration of the synchronization of light beams, a compensation plate may not be set up; or one side of the dual optical fiber collimators can be used as the optical input end and one side of a single optical fiber collimator is used as the optical output end.

Particular embodiments of the subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve desirable results. As one example, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous. 

What is claimed is:
 1. A magneto-optic switch, comprising: a plurality of optical components positioned in order along a light path comprising: a single optical fiber collimator, a first pair of refraction crystals, a first half wave plate assembly, refraction components, a second half wave plate assembly, a second pair of refraction crystals, and a dual fiber optic collimator, wherein a first side of the refraction components near the first half wave plate assembly includes a first Faraday effect element, a second side of the refraction components near the second half wave plate assembly includes an optic rotation assembly, the optic rotation assembly having a magnetic field generating component positioned outside the first Faraday effect element.
 2. The magneto-optic switch of claim 1, wherein the single optical fiber collimator is single core light beam expansion collimator and wherein a light beam expansion optical fiber is installed in the single core light beam expansion collimator.
 3. The magneto-optic switch of claim 1, wherein the dual optical fiber collimator is a dual core light beam expansion optical fiber collimators and wherein two light beam expansion optical fibers are installed in the dual core light beam expansion optical fiber collimator.
 4. The magneto-optic switch of claim 1, wherein the first Faraday effect element of the optic rotation assembly, the refraction components, the optic rotation component, and the magnetic field generating component are integrally packaged.
 5. The magneto-optic switch of claim 1 wherein the optic rotation component is a second Faraday effect element.
 6. The magneto-optic switch of claim 5, wherein the second Faraday effect element is located inside the magnetic generating component.
 7. The magneto-optic switch of claim 1, wherein the optic rotation component is a half wave plate.
 8. The magneto-optic switch of claim 1, wherein the refraction component is a Wollaston prism or a pair of mutually adjacent wedge dual refraction crystals.
 9. The magneto-optic switch of claim 1, wherein the first half wave plate assembly has a first a half wave plate, the first half wave plate being located on a light path of a light beam emitted from the first dual refraction crystals.
 10. The magneto-optic switch of claim 7, wherein the second half wave plate assembly has a second half wave plate, the second half wave plate being located on a light path of a light beam emitted from the second dual refraction crystals.
 11. The magneto-optic switch according to claim 8, wherein the second half wave plate assembly includes a compensation plate, the compensation plate being located on the light path of another light beam where the second half wave plate is located.
 12. The magneto-optic switch of claim 1, wherein the first half wave plate assembly and the second half wave plate assembly, respectively, include two half wave plates, the two half wave plates in the same set of half wave plate assemblies are respectively located on the light paths of two light beams emitted from the first dual refraction crystals. 